It is well known in vehicle bodies to install a weatherstrip around a door opening of the body so that closing the door against the weatherstrip seals the door opening against the entry of water. The weatherstrip conventionally includes a U-shaped cross-sectional portion with interior ribs which are adapted to engage over a sheet metal flange on the periphery of the vehicle body opening. A tubular elastomeric portion is interal with the U-shaped cross-sectional portion and projects outwardly of the door opening to be engaged by the door when the door is closed.
It is characteristic of such U-shaped cross-sectional weatherstrip that bending the weatherstrip around the corners of a door opening causes the weatherstrip to tend to twist. Such twisting may complicate the installation of the weatherstrip onto the flange of the door opening. The need for torsionally rigid weatherstrips is heightened by the advent of robotic installation of weatherstrips such as disclosed in U.S. Pat. No. 4,715,110, issued Dec. 29, 1987, Apparatus of a Robot for Installing Weather Stripping in a Door or Like Opening, Stephen St. Angelo et al, assigned to the assignee of this invention. Robotic installation of weatherstrips is facilitated if the weatherstrip is consistently capable of being bent by the robot tool without twisting.
Accordingly, it is desirable to provide a weatherstrip which is capable of bending without twisting. The tendency to twist is determined by the manufacturing variables such as the composition of the elastomeric material, the rigidity of a sheet metal or wire backbone incorporated into the U-shaped cross-section, and other manufacturing variables.
It would be desirable to provide a device for measuring the torsional rigidity of a weatherstrip, that is, the resistance of such a weatherstrip to twisting upon being bent. By testing weatherstrips for this resistance to twisting, weatherstrips could be consistently manufactured.